master(dm): support extra SHOW FULL TABLES columns from PolarDB-X by GMHDBJD · Pull Request #12481 · pingcap/tiflow

GMHDBJD · 2026-01-07T06:00:06Z

What problem does this PR solve?

Issue Number: close #12569

What is changed and how it works?

add a DM-local conn.GetTables helper for table discovery
keep the original SHOW FULL TABLES ... WHERE Table_Type != 'VIEW' behavior for normal MySQL/TiDB results
ignore extra columns after the first two scan targets so PolarDB-X 4-column results are accepted
add regression tests for both standard 2-column results and PolarDB-X-style 4-column results

Check List

Tests

Unit test: go test ./dm/pkg/conn -run 'TestGetTables|TestFetchAllDoTables'
Build/compile check: go test ./dm/pkg/checker ./dm/master -run '^$'

Questions

Will it cause performance regression or break compatibility?

No. Existing behavior for standard upstreams is kept unchanged. The parsing only becomes more permissive for extra result columns.

Do you need to update user documentation, design documentation or monitoring documentation?

No.

Release note

Support PolarDB-X SHOW FULL TABLES results with extra columns in DM table discovery.

…istency

gemini-code-assist · 2026-01-07T06:00:24Z

Summary of Changes

Hello @GMHDBJD, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request undertakes a refactoring effort to enhance code consistency by relocating the GetTables utility function. Previously residing in the dbutil package, this function has now been moved to dm/pkg/conn/db.go, centralizing database-related table retrieval logic. All instances where dbutil.GetTables was invoked have been updated to correctly reference the new conn.GetTables function, streamlining dependencies and improving maintainability.

Highlights

GetTables Function Relocation: The GetTables utility function has been moved from github.com/pingcap/tidb/pkg/util/dbutil to dm/pkg/conn/db.go to centralize database connection-related utilities.
Dependency Update: Imports and call sites across dm/master/openapi_view.go and dm/pkg/checker/onlineddl.go have been updated to reflect the new location of the GetTables function, now referencing conn.GetTables.
Code Consistency: This refactoring improves code consistency by consolidating database table retrieval logic within the conn package, reducing reliance on external dbutil for this specific functionality.

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gemini-code-assist

Code Review

This pull request refactors the code to use conn.GetTables instead of dbutil.GetTables, which is a good improvement for code organization. The implementation of the new conn.GetTables function is mostly correct, but I've suggested a couple of minor improvements for consistency and idiomatic Go.

A more critical issue is that the unit tests in dm/pkg/conn/db_test.go and dm/master/openapi_view_test.go appear to be broken by this change. They still mock the old SQL query from dbutil.GetTables (SHOW FULL TABLES ... WHERE ...). Please update the mocked queries to SHOW FULL TABLES IN ... without the WHERE clause to match the new implementation in conn.GetTables.

gemini-code-assist · 2026-01-07T06:02:40Z

+	if len(cols) < 2 {
+		return nil, errors.New("SHOW FULL TABLES returned less than 2 columns")
+	}


For consistency with the error handling in this package, it's better to return a terror error instead of a raw error created with errors.New. You can use terror.ErrDBUnExpect.Generate for this.

Suggested change

if len(cols) < 2 {

return nil, errors.New("SHOW FULL TABLES returned less than 2 columns")

}

if len(cols) < 2 {

return nil, terror.ErrDBUnExpect.Generate("SHOW FULL TABLES returned less than 2 columns")

}

gemini-code-assist · 2026-01-07T06:02:40Z

+		var dummy interface{}
+		scanArgs[i] = &dummy


This loop for creating dummy scan arguments can be made more efficient and idiomatic. Instead of declaring a new dummy variable in each iteration, you can allocate space for the columns you want to ignore directly. Using sql.RawBytes is a good practice for this as it can avoid extra allocations.

Suggested change

var dummy interface{}

scanArgs[i] = &dummy

scanArgs[i] = new(sql.RawBytes)

codecov · 2026-03-23T09:14:19Z

Codecov Report

❌ Patch coverage is 76.31579% with 9 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (master@abbaf8d). Learn more about missing BASE report.
⚠️ Report is 1 commits behind head on master.
✅ All tests successful. No failed tests found.

Additional details and impacted files

Components	Coverage Δ
cdc	`57.3464% <ø> (?)`
dm	`49.1038% <76.3157%> (?)`
engine	`50.6997% <ø> (?)`

Flag	Coverage Δ
cdc	`57.3464% <ø> (?)`
unit	`53.3819% <76.3157%> (?)`

Flags with carried forward coverage won't be shown. Click here to find out more.

@@             Coverage Diff             @@
##             master     #12481   +/-   ##
===========================================
  Coverage          ?   53.3819%           
===========================================
  Files             ?       1011           
  Lines             ?     139905           
  Branches          ?          0           
===========================================
  Hits              ?      74684           
  Misses            ?      59614           
  Partials          ?       5607

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GMHDBJD · 2026-03-23T12:44:51Z

/retest

joechenrh · 2026-03-25T05:30:49Z

+	return tables, errors.Trace(rows.Err())
+}
+
+func escapeName(name string) string {


Not related to this PR, but I found that there are three places in TiDB with this same (unexported) function 😂

ti-chi-bot · 2026-03-25T05:31:26Z

@joechenrh: adding LGTM is restricted to approvers and reviewers in OWNERS files.

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OliverS929 · 2026-03-25T09:02:43Z

 	}
 	defer baseDB.Close()
-	tableList, err := dbutil.GetTables(c.Request.Context(), baseDB.DB, schemaName)
+	tableList, err := conn.GetTables(c.Request.Context(), baseDB.DB, schemaName)


Could we add one 4-column regression for OpenAPIViewSuite.TestSourceAPI and one for the online-DDL checker path too? Right now the new coverage is mostly helper-level.

…20260325T091753Z # Conflicts: # sync_diff_inspector/source/source_test.go

OliverS929

LGTM overall. One small follow-up: please consider adding a test that actually enables config.OnlineDDLChecking or exercises OnlineDDLChecker.Check.

GMHDBJD · 2026-03-25T11:43:26Z

/retest

Benjamin2037

LGTM

ti-chi-bot · 2026-03-25T11:50:23Z

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Benjamin2037, joechenrh, OliverS929

The full list of commands accepted by this bot can be found here.

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Details

Needs approval from an approver in each of these files:

~~OWNERS~~ [Benjamin2037,OliverS929]
~~dm/OWNERS~~ [Benjamin2037]

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ti-chi-bot · 2026-03-25T11:50:25Z

[LGTM Timeline notifier]

Timeline:

2026-03-25 10:18:00.230622887 +0000 UTC m=+349876.266693167: ☑️ agreed by OliverS929.
2026-03-25 11:50:24.431344606 +0000 UTC m=+355420.467414866: ☑️ agreed by Benjamin2037.

GMHDBJD · 2026-03-25T14:37:20Z

/retest

refactor(conn): replace dbutil.GetTables with conn.GetTables for cons…

51906e6

…istency

ti-chi-bot bot added do-not-merge/needs-linked-issue release-note Denotes a PR that will be considered when it comes time to generate release notes. area/dm Issues or PRs related to DM. size/M Denotes a PR that changes 30-99 lines, ignoring generated files. labels Jan 7, 2026

gemini-code-assist bot reviewed Jan 7, 2026

View reviewed changes

dm: refine PolarDB-X SHOW FULL TABLES compatibility

02b3e49

ti-chi-bot bot added size/L Denotes a PR that changes 100-499 lines, ignoring generated files. and removed size/M Denotes a PR that changes 30-99 lines, ignoring generated files. labels Mar 23, 2026

GMHDBJD changed the title ~~refactor(conn): replace dbutil.GetTables with conn.GetTables for cons…~~ master(dm): support extra SHOW FULL TABLES columns from PolarDB-X Mar 23, 2026

GMHDBJD added type/bugfix This PR fixes a bug. and removed do-not-merge/needs-linked-issue labels Mar 23, 2026

ti-chi-bot bot added the do-not-merge/needs-triage-completed label Mar 23, 2026

ti-chi-bot bot removed the do-not-merge/needs-triage-completed label Mar 23, 2026

joechenrh approved these changes Mar 25, 2026

View reviewed changes

OliverS929 reviewed Mar 25, 2026

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Comment thread dm/pkg/conn/table.go

OliverS929 reviewed Mar 25, 2026

View reviewed changes

Comment thread dm/pkg/conn/db_test.go

GMHDBJD added 2 commits March 25, 2026 17:53

dm,sync-diff: cover extra SHOW FULL TABLES columns

6155c52

Merge remote-tracking branch 'upstream/master' into tiflow2/pr-12481-…

9a6b0a4

…20260325T091753Z # Conflicts: # sync_diff_inspector/source/source_test.go

OliverS929 approved these changes Mar 25, 2026

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ti-chi-bot bot added the needs-1-more-lgtm Indicates a PR needs 1 more LGTM. label Mar 25, 2026

Benjamin2037 approved these changes Mar 25, 2026

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ti-chi-bot bot added the lgtm label Mar 25, 2026

ti-chi-bot bot added approved and removed needs-1-more-lgtm Indicates a PR needs 1 more LGTM. labels Mar 25, 2026

ti-chi-bot bot merged commit 8c5244d into pingcap:master Mar 25, 2026
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	var dummy interface{}
	scanArgs[i] = &dummy
	scanArgs[i] = new(sql.RawBytes)

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